From patchwork Mon Jun 21 22:50:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergey Ryazanov X-Patchwork-Id: 12335903 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BA8EC4743C for ; Mon, 21 Jun 2021 22:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A45661164 for ; Mon, 21 Jun 2021 22:51:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232421AbhFUWxf (ORCPT ); Mon, 21 Jun 2021 18:53:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232362AbhFUWx3 (ORCPT ); Mon, 21 Jun 2021 18:53:29 -0400 Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1C1FC061766 for ; Mon, 21 Jun 2021 15:51:12 -0700 (PDT) Received: by mail-lj1-x236.google.com with SMTP id s22so27437091ljg.5 for ; Mon, 21 Jun 2021 15:51:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=zcdADzIGh+z3t+SaH4RHteH4RWCo6WcuMAbfzh1uCAw=; b=eBf1uabi1uionfaYTbnmSj8afVcTCtsuOxiRLm5O9LeNJGvgQ6Cxyo4oPwmvuyDIYI fK3RR2XcOiWPUqwlxCtzizWnipZtYgQlMbasuXY9vTyXr662C5ipiJa4rEvnCNK/kR9i 7J+UXlU0vDAS+gRuwwisBB5S1SW58YBktv2tcQA6JSBnQOc4MA/lro5JmPSp4ftpzaa7 p7LJU7HMo2VtI72LB9Onp3Abxd+8UAM1eZ5Ty0BSXMhZ4vkfni4FzHjcXf3TkM62KWmz EAqHkJsBPlcBB+zL7o0zH/erXOJC0mZoV0Bt7MfYJli6BHjciZ/SR0VClAQd0qS/2Z40 HmeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=zcdADzIGh+z3t+SaH4RHteH4RWCo6WcuMAbfzh1uCAw=; b=rIAqsMvaY/nX+2wUKKMxDIdROR16z20YBT8wt4w5/GRqeYf6kfTAXfGX27w5/SWTpx 2v2yiJmCSfNontW3Z1aJdzHgX4mmZCcU1A2jjfWboGWy5ChBCHSxl2wvz4FMiPvBYeIk Vg9Bbg08T/vcD42SzsjjXMUQ7evBgAMsat8cBK25FchM7qSuD6cA+3g03jb6ImYzYh68 FmBBSy0Ve3R1dDLVs0TseX+lDxs9SzOCxE7nOMOswRmQy/9+oS8wHLCvFSyYaxQCGSVf jnmMd2MDP/HZLa0Dl7RZLIOyqkr+hw8u/rUADifGXM+N4+RKzXdLMbRjDUSnL0N8l20Q jwhQ== X-Gm-Message-State: AOAM530pui9HB8ZfJPQiu+vWZWTy2jUY09HURuWz5JaKVPsihxQbg1Jr 1sYee54NV9SCRgIfqit7KcQ= X-Google-Smtp-Source: ABdhPJzRrQLbZtnRt0gq7Ezmxrtqr2RG8qZQiwfSTPfTFJx1XaaNHVXjSTQLQ16oSlivxpssh20oTA== X-Received: by 2002:a2e:894e:: with SMTP id b14mr462895ljk.112.1624315871323; Mon, 21 Jun 2021 15:51:11 -0700 (PDT) Received: from rsa-laptop.internal.lan ([217.25.229.52]) by smtp.gmail.com with ESMTPSA id x207sm124826lff.53.2021.06.21.15.51.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Jun 2021 15:51:10 -0700 (PDT) From: Sergey Ryazanov To: Loic Poulain , Johannes Berg , "David S. Miller" , Jakub Kicinski Cc: netdev@vger.kernel.org Subject: [PATCH net-next v2 07/10] wwan: core: no more hold netdev ops owning module Date: Tue, 22 Jun 2021 01:50:57 +0300 Message-Id: <20210621225100.21005-8-ryazanov.s.a@gmail.com> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210621225100.21005-1-ryazanov.s.a@gmail.com> References: <20210621225100.21005-1-ryazanov.s.a@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The WWAN netdev ops owner holding was used to protect from the unexpected memory disappear. This approach causes a dependency cycle (driver -> core -> driver) and effectively prevents a WWAN driver unloading. E.g. WWAN hwsim could not be unloaded until all simulated devices are removed: ~# modprobe wwan_hwsim devices=2 ~# lsmod | grep wwan wwan_hwsim 16384 2 wwan 20480 1 wwan_hwsim ~# rmmod wwan_hwsim rmmod: ERROR: Module wwan_hwsim is in use ~# echo > /sys/kernel/debug/wwan_hwsim/hwsim0/destroy ~# echo > /sys/kernel/debug/wwan_hwsim/hwsim1/destroy ~# lsmod | grep wwan wwan_hwsim 16384 0 wwan 20480 1 wwan_hwsim ~# rmmod wwan_hwsim For a real device driver this will cause an inability to unload module until a served device is physically detached. Since the last commit we are removing all child netdev(s) when a driver unregister the netdev ops. This allows us to permit the driver unloading, since any sane driver will call ops unregistering on a device deinitialization. So, remove the holding of an ops owner to make it easier to unload a driver module. The owner field has also beed removed from the ops structure as there are no more users of this field. Signed-off-by: Sergey Ryazanov Reviewed-by: Loic Poulain --- v1 -> v2: * fix a comment before wwan_unregister_ops() in the mhi/net.c drivers/net/mhi/net.c | 3 +-- drivers/net/wwan/wwan_core.c | 10 ---------- drivers/net/wwan/wwan_hwsim.c | 1 - include/linux/wwan.h | 2 -- 4 files changed, 1 insertion(+), 15 deletions(-) diff --git a/drivers/net/mhi/net.c b/drivers/net/mhi/net.c index 6aa753387372..ffd1c01b3f35 100644 --- a/drivers/net/mhi/net.c +++ b/drivers/net/mhi/net.c @@ -383,7 +383,6 @@ static void mhi_net_dellink(void *ctxt, struct net_device *ndev, } static const struct wwan_ops mhi_wwan_ops = { - .owner = THIS_MODULE, .priv_size = sizeof(struct mhi_net_dev), .setup = mhi_net_setup, .newlink = mhi_net_newlink, @@ -436,7 +435,7 @@ static void mhi_net_remove(struct mhi_device *mhi_dev) struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev); struct mhi_controller *cntrl = mhi_dev->mhi_cntrl; - /* rtnetlink takes care of removing remaining links */ + /* WWAN core takes care of removing remaining links */ wwan_unregister_ops(&cntrl->mhi_dev->dev); if (create_default_iface) diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c index ec6a69b23dd1..b634a0ba1196 100644 --- a/drivers/net/wwan/wwan_core.c +++ b/drivers/net/wwan/wwan_core.c @@ -929,11 +929,6 @@ int wwan_register_ops(struct device *parent, const struct wwan_ops *ops, return -EBUSY; } - if (!try_module_get(ops->owner)) { - wwan_remove_dev(wwandev); - return -ENODEV; - } - wwandev->ops = ops; wwandev->ops_ctxt = ctxt; @@ -960,7 +955,6 @@ static int wwan_child_dellink(struct device *dev, void *data) void wwan_unregister_ops(struct device *parent) { struct wwan_device *wwandev = wwan_dev_get_by_parent(parent); - struct module *owner; LIST_HEAD(kill_list); if (WARN_ON(IS_ERR(wwandev))) @@ -976,8 +970,6 @@ void wwan_unregister_ops(struct device *parent) */ put_device(&wwandev->dev); - owner = wwandev->ops->owner; /* Preserve ops owner */ - rtnl_lock(); /* Prevent concurent netdev(s) creation/destroying */ /* Remove all child netdev(s), using batch removing */ @@ -989,8 +981,6 @@ void wwan_unregister_ops(struct device *parent) rtnl_unlock(); - module_put(owner); - wwandev->ops_ctxt = NULL; wwan_remove_dev(wwandev); } diff --git a/drivers/net/wwan/wwan_hwsim.c b/drivers/net/wwan/wwan_hwsim.c index c1e850b9c087..a8582a58a385 100644 --- a/drivers/net/wwan/wwan_hwsim.c +++ b/drivers/net/wwan/wwan_hwsim.c @@ -94,7 +94,6 @@ static void wwan_hwsim_netdev_setup(struct net_device *ndev) } static const struct wwan_ops wwan_hwsim_wwan_rtnl_ops = { - .owner = THIS_MODULE, .priv_size = 0, /* No private data */ .setup = wwan_hwsim_netdev_setup, }; diff --git a/include/linux/wwan.h b/include/linux/wwan.h index 34222230360c..e1981ea3a2fd 100644 --- a/include/linux/wwan.h +++ b/include/linux/wwan.h @@ -128,14 +128,12 @@ void *wwan_port_get_drvdata(struct wwan_port *port); /** * struct wwan_ops - WWAN device ops - * @owner: module owner of the WWAN ops * @priv_size: size of private netdev data area * @setup: set up a new netdev * @newlink: register the new netdev * @dellink: remove the given netdev */ struct wwan_ops { - struct module *owner; unsigned int priv_size; void (*setup)(struct net_device *dev); int (*newlink)(void *ctxt, struct net_device *dev,